Module One: DEFINITIONS/CONCEPTS OF ECOLOGY; HEALTH

The environment is everything around you. It includes all the living things (such as plants and animals)
and the non-living things (such as air, water, and sunlight) with which you interact. As an individual, you are
part of nature and live in the environment. Despite humankind’s many scientific and technological advances,
our lives depend on sunlight and the earth for clean air and water, food, shelter, energy, fertile soil, a livable
climate, and other components of the planet’s life-support system. Environmental science is a study of
connections nature. It is an interdisciplinary study of: how the earth (nature) works and has survived and
thrived; how humans interact with the environment; and how we can live more sustainably.
A key component of environmental science is ecology, the branch of biology that focuses on how living
organisms interact with the living and non-living parts of their environment. Every organism is a member of a
certain species: a group of organisms that have distinctive or unique traits and, for sexually reproducing
organisms, can mate and produce fertile offspring. A major focus of ecology is the study of ecosystems. An
ecosystem is a set of organisms within a defined area of land or volume of water that interact with one another
and with their environment of non-living matter and energy. For example, a forest ecosystem consists of plants
(especially trees), animals, and tiny decomposers that recycle its chemicals, all interacting with one another and
with solar energy and the chemicals in its air, water, and soil.
Ecology is the study of the relationships between living organisms, including humans, and their physical
environment. Ecology considers organisms at the individual, population, community, ecosystem and biosphere
level. Ecology is usually defined as the study of interactions of organisms with their environments and each
other. More pointedly, it can be defined as the study of the distribution and abundance of organisms. Among
other things, ecology is the study of:
 the abundance, biomass, and distribution of organisms in the context of the environment.
 life processes, antifragility, interactions and adaptations.
 the movement of materials and energy through living communities.
 the successional development of ecosystems
 cooperation, competition and predation within and between species.
 patterns of biodiversity and its effect on ecosystem processes.
Ecology has practical applications in conservation biology, wetland management, natural resources
management, urban planning, community health, economics, applied science and human social interaction
(human ecology).

BASIC DEFINITION OF HUMAN ECOLOGY

Human ecology is the study of the interactions of humans with their environments, or the study of the
distribution and abundance of humans. This definition is based directly on conventional definitions of biological
ecology. Thus, using the term “human ecology” actually expresses a broad ambition to understand human
behavior (Barrett, 2005). So, it is the study of the relationships between humans and their environments and it is
a field with a large scope and complex history. It arose out of multiple disciplines: animal biology,
anthropology, geology, ecology, and sociology in the early 1900s as scientists struggled to make sense of the
impact of humans on the man-made and natural environment and the impact of environments on the social
systems of humans. Human ecology is also viewed by many as a methodology or framework for studying
human activities and social institutions, often in conjunction with the health and functioning of the natural
environment (Jaiswal, 2013).

THE ORIGINS OF HUMAN ECOLOGY

Since ancient times, there have been many attempts to explain events in terms of environmental
influences on human behavior. Astrology represents one early system of thought relating environmental forces
to human actions. Although wholly discredited as a scientific theory by modern astronomy, the belief that the
movement of the stars controls human destiny retains a strong hold on the popular imagination, as evidenced by
the appearance of astrological advice columns in many daily newspapers.
In a vein more compatible with modern scientific thought, the ancient Greek philosophers recognized
that man was both influenced by nature and a force for change in the environment. It was suggested, for
example, that the different forms of political organization of the Greek city states and the Eastern empires
reflected the influences of climate on the personalities of their citizen. This theme later was developed by
Montesquieu and other French writers of the Enlightenment and advocated in recent times by the American
geographer Samuel Huntington.
Other classical writers commented on the destruction of the natural landscape of Attica and North Africa
resulting from deforestation and overgrazing, a theme taken up in the mid-1800s by George P. Marsh, whose
book, Man and Nature, or, Physical Geography as Modified by Human Action was a precursor of the ecological
catastrophe writings so popular recently. These early writings, however, were generally anecdotal rather than
presenting a coherent theory of human-environment relationships. It was only with the development of
geography and anthropology as scientific disciplines in the latter part of the nineteenth century that human
ecology became the subject of systematic study. The first theoretical approach to be tried, however, was that of
environmental determinism: a false start that greatly retarded subsequent development of human ecology.

HEALTH
Although we use the term health almost unconsciously, few people understand the broad scope of the
word. For some, health simply means the antithesis of sickness. To others, it means being in good physical
shape and able to resist illness. Still others use the term such as wellness or wellbeing to include a wide array of
factors that lead to positive health status. World Health Organisation defined health as a state of complete
physical, mental and social well-being and not merely the absence of disease and infirmity.
ECOLOGY AND HEALTH
The term ‘ecology’ pertains broadly to the interrelations between organisms and their environments (Hawley
1950). From its early roots in biology, the ecological paradigm has evolved within several disciplines (e.g.,
sociology, psychology, economics, and public health) to provide a general framework for understanding
people’s transactions with their physical and sociocultural surroundings (e.g., Barker 1968, Bronfenbrenner
1979, Park et al. 1925). The field of ecology and health examines the direct and interactive e ffects of conditions
in the physical and sociocultural environment on the physiological, emotional, and social well-being of
individuals and groups (cf., Duhl 1996, Moos 1979, Stokols 1996). Ecological analyses provide more
integrative and comprehensive explanations for the joint influence of biogenetic, psychological, behavioral,
sociocultural, and physical environmental factors on human well-being, than do narrowly-gauged biomedical,
behavioral, and environmental theories.
Module Two: A NEW PERSPECTIVES OF HEALTH BY THE WORLD HEALTH ORGANISATION
(WHO)
The World Health Organization (WHO) was founded in 1948 with an ambitious objective ‘the
attainment by all peoples of the highest possible level of health’. Its constitution defined 22 wide-ranging
functions, of which the first was ‘to act as the directing and coordinating authority
on international health work’. The constitution of WHO is notable for the scope and breadth of the agenda it
lays out for the organization. Health is described as ‘a state of complete physical, mental and social well-being
and not merely the absence of disease or infirmity’ and the enjoyment of the highest attainable standard of
health as a fundamental human right. Governments have a responsibility to provide ‘adequate health and social
measures’. The constitution sets out 22 functions for WHO, which cover almost every conceivable activity
linked to the promotion of health.
Core functions of WHO
i. Providing leadership on matters critical to health and engaging in partnerships where joint action is
needed;
ii. Shaping the research agenda and stimulating the generation, translation and dissemination of valuable
knowledge;
iii. Setting norms and standards, and promoting and monitoring their implementation;
iv. Articulating ethical and evidence-based policy options;
v. Providing technical support, catalysing change, and building sustainable institutional capacity;
vi. Monitoring the health situation and assessing health trends
Programmes and priority setting
As agreed at the February 2012 member-states meeting, the categories of WHO activities
proposed for priority setting would be as follows:
  Communicable diseases: reducing the burden of communicable diseases, including HIV/AIDS,
tuberculosis, malaria and neglected tropical diseases.
 Non-communicable diseases: reducing the burden of non-communicable diseases, including heart
disease, cancer, lung disease, diabetes and mental disorders, as well as disability, and injuries, through
health promotion and risk reduction, prevention, treatment and monitoring of non-communicable
diseases and their risk factors.
 Promoting health through the life-course: reducing morbidity and mortality and improving health during
pregnancy, childbirth, the neonatal period, childhood and adolescence; improving sexual and
reproductive health; and promoting active and healthy ageing, taking into account the need to address
determinants of health and internationally agreed development goals, in particular the health-related
Millennium Development Goals.
 Health systems: support the strengthening of health systems with a particular focus on achieving
universal coverage, strengthening human resources for health, health information systems, facilitating
transfer of technologies, promoting access to affordable, quality, safe and efficacious medical products,
and promoting health services research.
 Preparedness, surveillance and response: surveillance and effective response to disease outbreaks, acute
public health emergencies and the effective management of health-related aspects of humanitarian
disasters to contribute to health security.
 Corporate services/enabling functions: organizational leaderships and corporate services that are
required to maintain the integrity and efficient functioning of WHO.
Module Three: MEDICAL VERSUS ECOLOGICAL MODELS OF HEALTH
Health is a state of complete physical, social and mental well-being and not merely the absence of
disease or infirmity. The enjoyment of the highest attainable standard of health is one of the fundamental rights
of every human being, without distinction of race, religion, political beliefs or economic and social conditions
(World Health Organisation). The ways in which health, illness and disease are defined depends on different
factors and models, For instance the way the practitioner defines health is different from the way other people in
the society defines it. There has always been diversity in the theoretical of health and illness in the western
culture. Though the models of health may vary, these models play a defining role, signifying what should be or
not be the object of public health concern.
Environment is the circumstances, objects, or conditions by which one is surrounded or the complex of
climatic, edaphic (soil-based), and biotic factors that act upon an organism or an ecologic community. Human
environment includes what man occupies now including land and water forms. It is broken into six systems-
climate, hydrological, edaphic, plant, animal and saprophyte. Man is included in animal system. Public Health
Definition of the Environment - all that which is external to the individual host. It can be divided into physical,
biological, social, and cultural factors, any or all of which can influence health status in populations. In modern
concept, environment includes not only the water, air and soils that form environment but also the social and
economic conditions under which we live. In Nigeria, as in many countries, the environment is influenced by
human activities. Understanding the human activities in the community is important in ensuring a safe
environment for present and future generations. In this unit, the environment is defined, components of
environment highlighted and environmental hazards which human are exposed to and the health effects.
SOCIAL AND MEDICAL HEALTH MODEL: CONTRAST
The social model of health places importance on the changes that needs to be made by society,
empowering people to be in charge of their own health and lifestyles, in order to make the population healthier.
The medical model defines health as absence of disease, it informs the most powerful and influential discourse
about health. The medical model is the most main system of medical knowledge within the western world; its
activity is the treatment of disease in individuals. It’s the model that quite defines health narrowly.

Social model of health key components involves health being determined by a broad range of social,
environmental and economic factors as not just biomedical risk factors, it also act to reduce inequalities that has
to do with age, gender, race, culture, socioeconomic status and location because equity is the main point for
health service delivery. The key component of the medical model of health involves the standard analytical
format process; underlying the model is the implicit assumption that the illness described by the person, now
called patient, indicate a disordered part, or pathology, called the disease or disorder which is the cause of the
illness.

The social model of health differences when compared to the medical model of health are as follows:-

 The social model of health is focus more on the environment, social, and environmental determinants of
health, not just biomedical determinants. The medical model is centred on individual as a patient.
 The medical model has a core structure of analysis by which symptoms and physical signs known as
illness are reduced to more specific disordered part while the social determinant of health is the social
and environmental condition people work and live.
 Medical model deals with a specific disease with specific therapy while social model of health is based
on the understanding that in order for health gains to be present we need to meet the people’s basic
needs.
 In addition to the comparison, the social model of health takes into recognition the environmental and
social factors that affect health and produce inequities whereas the medical model serves well for illness
caused primarily by organic diseases, albeit with serious limitation when no specific cause or cure is
known.
  It is widely accepted that the medical model of health focuses primarily on the eradication of illness
through diagnosis and effective treatment. In comparison, the social model of health emphasis on
changes in the society and in people’s way of life to make the population healthier.

In conclusion, Human kind is believed to be the only one that does not allow nature to be just nature.
The most commonly accepted vision of healthcare is that improvements result from advancements in medical
science. Taking into consideration these models of health allows us to have a better knowledge of why some
people take care of their health easily than others.

OTHER MODELS OF HEALTH

Social Model of Health: This model emerged from the social model of disability, which has been strongly
advocated by the disability rights movement. It was developed as a reaction to the traditional medical model.
The social model of health examines all the factors which contribute to health such as social, cultural, political
and the environment. An example is poor housing: see diagram It is well documented that both stress and low
self-esteem can have a negative impact on health. “Low levels of autonomy and low self-esteem are likely to
relate to worse health.” (Marmot, 2003) Community Development and Health Network believes that
communities know that their health is being affected by a variety of issues. We also believe that communities
can and should be actively involved in identifying, planning, designing and implementing solutions to health
issues and unjust health inequalities.
Medical Model: Developed during the age of Enlightenment in the 18th Century, when the traditional natural
sciences began to dominate academia and medical practice. The belief that science could cure all illness and
disease has remained a core element of modern medicine. This concept of health may be easier to understand as
it makes health an attribute you can measure simply by determining if a disease is present or not. However the
strong emphasis on the absence of disease as an indicator of good health, and the overdependence on the
influence of medical science in health, ignores the power of other important influences.
Biopsychosocial Model: Developed by psychiatrist George Engel in 1977, and recognizes that many factors
affect health. It pays “explicit attention to humanness” (Engel, 1997). It views health as a scientific construct
and a social phenomenon. The model looks at the biological factors which affect health, such as age, illness,
gender etc. The psychological factors: individual beliefs and perceptions. The social: the community, the
presence or absence of relationships “We suffer when our interpersonal bonds are sundered and we feel solace
when they are reestablished” (Engel, 1997)
Salutogenic Model: Developed by sociologist Aaron Antonovsky and focuses how and why we stay well. This
model increases understanding of the relationship between stressors, coping and health.
Ecosystem Health: Humanity is part of and one among many in an environment that is being changed as result
of human activity: land use, climate change, population growth, resource depletion, pollution, urbanization, loss
of biodiversity, and other local and global processes all disrupt the natural self-regulation of the biosphere.
These changes harm people, domestic animals, wildlife, the oceans, and the forests. The crucial response has to
be to redesign our relations with the rest of nature. (Levins and Lopez 1999)

Module Four: NON-MEDICAL DETERMINANTS OF HEALTH (SOCIO-ECONOMIC STATUS AND

HEALTH)

Policy-makers, service providers and the general public have come to appreciate that the health of a
population is linked to factors beyond the health care system. An important aspect of this perspective focuses on
the role of the ‘determinants’ of health. Despite widespread commitment to a population health approach, many
decision-makers are struggling to address health determinants beyond a narrow scope of illness-related causes.
Most decision-makers and resources in the health sector are understandably focused on illness and disability-
related issues. The health sector, however, has a potentially leading role to play in addressing a much broader
range of determinants of health beyond medical determinants.

The Social Determinants of Health (SDH) are the non-medical factors that influence health outcomes.
They are the conditions in which people are born, grow, work, live, and age, and the wider set of forces and
systems shaping the conditions of daily life. These forces and systems include economic policies and systems,
development agendas, social norms, social policies and political systems. The SDH have an important influence
on health inequities i.e. the unfair and avoidable differences in health status seen within and between countries.
In countries at all levels of income, health and illness follow a social gradient: the lower the socioeconomic
position, the worse the health. The following list provides examples of the social determinants of health, which
can influence health equity in positive and negative ways:

 Income and social protection

 Education
 Unemployment and job insecurity
 Working life conditions
 Food insecurity
 Housing, basic amenities and the environment
 Early childhood development
 Social inclusion and non-discrimination
 Structural conflict
 Access to affordable health services of decent quality.

Research shows that the social determinants can be more important than health care or lifestyle choices
in influencing health. For example, numerous studies suggest that SDH account for between 30-55% of health
 outcomes. In addition, estimates show that the contribution of sectors outside health to population health
outcomes exceeds the contribution from the health sector. Addressing SDH appropriately is fundamental for
improving health and reducing longstanding inequities in health, which requires action by all sectors and civil
society.

DETERMINANTS OF HEALTH WITH EXAMPLES OF IMPLEMENTED INITIATIVES

Determinants Description Examples of Implemented Initiatives

Income and Health status improves at each Fee waivers for childbirth education; dental care for
Social Status step up the income and social adults living in poverty; poverty coalition
hierarchy. Higher income levels coordinator position; homeless shelter; food
affect living conditions such as security/poverty working group; subsidy program
safe housing and the ability to for home care clients; minimum wage advocacy;
buy sufficient and healthy food. income security programs for mental health clients.

Social Support Support from families, friends Localized, issue and disease-specific programs
Networks and communities is associated (new parents, fetal alcohol syndrome, hepatitis C,
with better health. The health mental illness); healthy aging; community kitchens;
effect of the support of family and grief counseling groups; caregiver support
friends who provide a caring and program; 12 step addictions programs; “seniors
supportive relationship may be as healthy community project”.
important as risk factors such as
smoking, physical activity,
obesity, and high blood pressure.

Education Health status improves with level Alternative high schools; health information at
of education. Education increases appropriate literacy levels; health centre helps
opportunities for income and job clients with their grade 12 equivalency test; “stay in
security and gives people a sense school” project; youth health centres in schools to
of control over their lives – key provide health promotion and counseling services
factors which influence health. (sexuality, relationships, addictions); literacy
assessment of residents; speech language and
occupational therapy in schools.
Employment Unemployment, under- Staff wellness programs (tobacco, physical activity,
and Working employment and stressful work etc.); leave of absence/financial assistance to
Conditions are associated with poorer health. improve education and skills for staff; farm safety
Those with more control over initiatives; occupational health and safety to private
their work and fewer stress- industry; employment equity policies; health centre
related demands on the job are assists clients with resumes and job search; low
healthier. threshold employment services; mental health
vocational rehabilitation program.
Social The values and norms of a society Safer cities program; in-home visitation program;
Environments affect the health and well-being language services program; mentoring programs;
of individuals and populations. “caring communities project”; drug strategy; sports
Social stability, recognition of programs for vulnerable children; supportive
diversity, safety, good environments coordinator; community health
relationships and cohesive impact assessment; community suicide prevention
communities provide a supportive team; development of a diversity lens to ensure that
society, which reduces or services meet the needs of the diverse population in
removes many risks to good the region.
health.
Physical Physical factors in the natural Schools and public health inspection; occupational
Environment environment (e.g., air and water health and safety teams; tobacco reduction; water
quality) are key influences on quality control and indoor air quality; food safety
health. Factors in the human-built programs; agricultural health and safety council;
environment, such as housing, smoke-free and scent-free policies; construction of
workplace safety, community and playgrounds and trails; housing support services for
road design, are also important people with mental health, addictions, and/or
influences. disabilities; traffic safety commission.
Personal Social environments that enable Health education initiatives (e.g., health fairs) for
Health and support healthy choices and various health issues, such as cancer, mental health,
Practices and lifestyles, as well as people’s heart health, HIV, diabetes, sexual health;
Coping Skills knowledge, behaviours, and methadone program; counseling and therapy
coping skills for dealing with life programs; smoking cessation program; promotion
in healthy ways, are key of physical activity at the community level; anger
influences on health. management, suicide prevention and self-esteem
programs.
Healthy Child The effect of prenatal and early Pre- and post-natal classes and visits;
Development childhood experiences on maternal/child nutrition programs; fetal alcohol
subsequent health, well-being, syndrome programs; hearing and speech programs;
coping skills, and competence is preschool programs; breast feeding friendly
very powerful. For example, a workplace; well baby clinics; youth health centres
low weight at birth links with in high schools; “kids first”, “baby first”, “early
health and social problems start”, “growing healthy families”, “nobody’s
throughout a person’s life. perfect parenting” programs; child protection.
Culture Culture comes from both personal Interpreter services; diversity training and services;
history and wider situational, First Nations, French and immigrant liaison
social, political, geographic, and workers; youth/women’s clinic; Aboriginal health
economic factors. Multicultural strategy; gang awareness committee; kinship
health issues demonstrate how centre; discrimination policy; primary health care
necessary it is to consider the centres for underserved populations; HIV/AIDS
interrelationships of physical, services and programs for vulnerable populations.
mental, spiritual, social, and
economic well-being.
Gender Gender refers to the many Women’s health programs; mom’s groups; young
different roles, personality traits, girls groups (to develop a healthy body image);
attitudes, behaviours, values, participating in development of provincial strategy;
 relative powers and influences violence intervention programs; paternity/maternity
which society assigns to the two leave policies; parenting classes for fathers; survey
sexes. Each gender has specific of rural women’s health; gender-based analysis;
health issues or may be affected men’s wellness fair; transgender health program.
in different ways by the same
issues.

Module Five: NEXUS BETWEEN HEALTH AND POVERTY

Poverty is defined as the inability to meet one’s basic economic needs. According to the World Bank
and the United Nations, 1.1 billion people (a number equal to the entire population of China and almost four
times the size of the U.S. population) struggle to survive on an income equivalent to less than $1.25 a day.
Poverty occurs when people are unable to meet their basic needs for adequate food, water, shelter, health, and
education. The good news is that the number of people living in extreme poverty has decreased by 500 million
since 1981. Poverty has a number of harmful environmental and health effects. Some of which are:

 Lack of access to adequate sanitation facilities

 Lack of access to enough fuel for heating and cooking
 Lack of access to electricity
 Lack of access to adequate health care
 Lack of access to clean drinking water
 Lack of access to adequate housing and;
 Lack of access to enough food for good health.

The daily lives of the world’s poor are focused on getting enough food, water, and cooking and heating
fuel to survive. Desperate for short-term survival, some of these individuals degrade forests, soil, grass lands,
fisheries, and wildlife, at an ever increasing rate. They do not have the luxury of worrying about long-term
environmental quality or sustainability. Even though the poor in developing countries have no choice but to use
few resources per person, their large population size leads to a high overall environmental impact.

Poverty is a major cause of ill health and a barrier to accessing health care when needed. This
relationship is financial: the poor cannot afford to purchase those things that are needed for good health,
including sufficient quantities of quality food and health care. But, the relationship is also related to other
factors related to poverty, such as lack of information on appropriate health-promoting practices or lack of voice
needed to make social services work for them.

Ill health, in turn, is a major cause of poverty. This is partly due to the costs of seeking health care,
which include not only out-of-pocket spending on care (such as consultations, tests and medicine), but also
transportation costs and any informal payments to providers. It is also due to the considerable loss of income
associated with illness in developing countries, both of the breadwinner, but also of family members who may
be obliged to stop working or attending school to take care of an ill relative. In addition, poor families coping
with illness might be forced to sell assets to cover medical expenses, borrow at high interest rates or become
indebted to the community.
What links poverty and poor health?

Poverty and poor health worldwide are inextricably linked. The causes of poor health for millions
globally are rooted in political, social and economic injustices. Poverty is both a cause and a consequence of
poor health. Poverty increases the chances of poor health. Poor health, in turn, traps communities in poverty.
Infectious and neglected tropical diseases kill and weaken millions of the poorest and most vulnerable people
each year.

What other links are there between poverty and poor health?

 The economic and political structures which sustain poverty and discrimination need to be transformed
in order for poverty and poor health to be tackled.
 Marginalised groups and vulnerable individuals are often worst affected, deprived of the information,
money or access to health services that would help them prevent and treat disease.
 Very poor and vulnerable people may have to make harsh choices knowingly putting their health at risk
because they cannot see their children go hungry.
 The cultural and social barriers faced by marginalised groups including indigenous communities can
mean they use health services less, with serious consequences for their health. This perpetuates their
disproportionate levels of poverty.
 The cost of doctors’ fees, a course of drugs and transport to reach a health centre can be devastating,
both for an individual and their relatives who need to care for them or help them reach and pay for
treatment. In the worst cases, the burden of illness may mean that families sell their property, take
children out of school to earn a living or even start begging.
 The burden of caring is often taken on by a female relative, who may have to give up her education as a
result, or take on waged work to help meet the household’s costs. Missing out on education has long-
term implications for a woman’s opportunities later in life and for her own health.
 Overcrowded and poor living conditions can contribute to the spread of airborne diseases such as
tuberculosis and respiratory infections such as pneumonia. Reliance on open fires or traditional stoves
can lead to deadly indoor air pollution. A lack of food, clean water and sanitation can also be fatal.

Module Six: INDICATORS FOR HEALTHY ENVIRONMENT

Your health depends on the environment around you. Environmental health is the study of how the
environment affects human health. It differs from the study of how humans affect the environment, because it
focuses on people’s health. Environmental health is not just about the health of the environment but whether the
environment is helping you stay healthy, or making you sick. Mans’ ill health can be traced to adverse
environmental factors such as water pollution, soil pollution, air pollution, food contamination, poor housing
conditions, , presence of animal reservoirs and insect vectors, among others. These factors pose constant threat
to man’s health.
Man is often responsible for the degradation of his environment through urbanization, industrialization
and other human activities. The health problems posed by environmental hazards vary from place to place. In
developing countries, the areas of water supply, sewage and solid waste disposal will be of great priority
followed by food hygiene and vector control. In industrialized countries, control of air pollution is of great
importance. The effective control of environment depends on the hazard in question. Generally it is through
health education, technology and legislation. Environmental health control is the responsibility of the Ministry
of Environment and Local Government Authorities but health care professionals must work with the agencies
and the people to get the best out of the environment for the health of the people
Components/Indicators of/for Healthy Environmental
1. Air hygiene and safety
2. Provision of safe and adequate supply of water
3. Proper management of solid waste
4. Proper sewage management
5. Safe guarding of food
6. Provision of good housing
7. Control of insect vectors and other pests
8. Control of animal reservoirs of infection and disinfection
9. Elimination of other hazards e.g. noise, radiation, climate change, global warming, acid rain